1. Field of the Invention
This invention relates to a photo-detecting device and more particularly to a device employing a storage type photo-sensor in which information stored according to light inputs is produced in the form of signals integrated in a real time and nondestructive manner.
2. Description of the Prior Art
Generally a storage type sensor storing an input signal such as information on light or the like becomes incapable of accurately detecting the signal amount received due to noises or the like under a condition where only a small input signal is stored. This necessitates continuous storing of information by the sensor at least until the signal amount stored at the sensor becomes detectable. In the meantime, control and processing circuits, etc. must be kept from using the output of the sensor.
In conventional practice, this problem is solved by repeatingly reading out the storage signal of the sensor and a length of time required before the storage signal of the sensor reaches a prescribed level is precalculated from a storage amount obtained for a certain storing time during the repeated read-out process. Whether or not the signal storage amount of the sensor has reached a detectable range is thus determined in a trial-and-error manner. In another conventional practice, an intensity detecting sensor is provided in addition to a storage type sensor for detecting the intensity of the signal of a photo-diode or the like; and whether or not the storage signal of the storage type sensor has reached a detectable range is determined on the basis of the output of the intensity detecting sensor.
However, it is a shortcoming of the former conventional practice that the signal must be repeatedly stored at the sensor before an adequate storage time is determined. Therefore, a long time is required for measurement. A shortcoming of the latter method, on the other hand, is that the signal storage amount of the storage type sensor cannot be accurately detected due to the positional difference between the storage type sensor and the intensity detecting sensor.
It is therefore an object of the present invention to provide a photo-detecting device wherein there is provided at least one photo-detecting means which includes a storage type photo-sensor producing information stored therein according to light inputs in the form of signals integrated in real time and in a nondestructive manner. The storage time of the photo-detecting means can be accurately determined in a short period of time.
It is another object of the invention to provide a photo-detecting device which is capable of detecting brightness from the output of the above photo-detecting means with an extremely simplified structural arrangement.
It is a further object of the invention to provide a photo-detecting device which is capable of stopping flash means from flashing by virtue of the output of the above photo-detecting means.
These and other objects and features of the invention will be apparent from the following detailed description of preferred embodiments thereof taken in conjunction with the accompanying drawings.